The present invention relates, in general, to a brachytherapy seed cartridge and, more particularly, to an improved brachytherapy seed cartridge including a removable seed drawer.
Prostatic cancer has been estimated to affect as many as one in three men. In the U.S. alone, this implies an estimated fifty-million patients who are candidates for treatment of prostatic cancer. Prior methods of treatment include surgical intervention, external radiotherapy, and other brachytherapy (interstitial radiation) techniques. A general discussion of the localized use of radiation therapy is found in Bagshaw, M. A., Kaplan, I. D. and Cox, R. C., Radiation Therapy for Localized Disease, CANCER 71: 939-952, 1993. Disadvantages associated with surgical intervention include impotence and incontinence. External radiotherapy may have deleterious effects on surrounding normal tissues (e.g., the bladder, the rectum, and the urethra). In contrast, brachytherapy diminishes complications such as impotence and incontinence, and allows a higher and more concentrated radiation dose to be delivered to the prostate gland as compared to external radiotherapy. An additional advantage of brachytherapy is that treatment can be accomplished within a matter of days as compared to weeks, greatly reducing radiation exposure of the adjacent organs.
Prostate brachytherapy can be divided into two categories, based upon the radiation level used. The first category is temporary implantation, which uses high activity sources, and the second category is permanent implantation, which uses lower activity sources. These two techniques are described in Porter, A. T. and Forman, J. D., Prostate Brachytherapy, CANCER 71: 953-958, 1993. The predominant radioactive sources used in prostate brachytherapy include iodine-125, palladium-103, gold-198, ytterbium-169, and iridium-192. Prostate brachytherapy can also be categorized based upon the method by which the radioactive material is introduced into the prostate. For example, a open or closed procedure can be performed via a suprapubic, transperineal or retropubic approach.
While there are various therapies to treat this condition, one of the more successful approaches is to expose the prostate gland to radiation by implanting radioactive seeds. The seeds are implanted in rows and are carefully spaced to match the specific geometry of the patient""s prostate gland and to assure adequate radiation dosages to the tissue. Current techniques to implant these seeds include loading them one at a time into the cannula of a needle-like insertion device, which may be referred to as a brachytherapy needle. Between each seed may be placed a spacer, which may be made of catgut. In this procedure, a separate brachytherapy needle is loaded for each row of seeds to be implanted.
In brachytherapy procedures, large amounts of time are currently consumed loading radio active seeds and spacers into the brachytherapy needles. Further, once the needles are loaded, it becomes difficult to verify the dosage (i.e. number of seeds) or to check the level of radioactivity in any individual seed or seeds. Thus, it is preferable to load the appropriate number of seeds and spacers into a cartridge which may then be used to visually verify the number of seeds or to conveniently extract one or more seeds to verify the radio activity of the seeds prior to loading the seeds into a brachytherapy needle. It is also preferable, in certain circumstances, to sterilize the seeds prior to loading them into the brachytherapy needles, allowing the surgeon to review the dosage after sterilization and immediately prior to implantation.
It would, therefore, be advantageous to design a brachytherapy seed cartridge which decreases the time required to check dosage and radioactivity. It would further be advantageous to design a brachytherapy seed cartridge which facilitates loading of brachytherapy needles prior to the brachytherapy procedure. In particular, it would be advantageous to design a brachytherapy seed cartridge which is adapted to organize, view and conveniently add or remove seeds and spacers.
The present invention is directed to a seed cartridge assembly including a cartridge body, a seed drawer slideably disposed within the cartridge body, a radiation shield slideably disposed around the cartridge body and a seed retainer in the seed drawer. Further embodiments of the present invention include a seed cartridge assembly as described above including a gravity lock between the seed drawer and the cartridge body. Further embodiments of the present invention include a seed cartridge assembly as described above, wherein the cartridge body includes a magnification lens positioned above the seed drawer. Further embodiments of the present invention include a seed cartridge assembly as described above wherein a seed channel extends axially along the seed drawer and a plurality of vents extending from the seed channel to an exterior surface of the seed drawer. Further embodiments of the present invention include a seed cartridge assembly as described above wherein the gravity lock includes a moveable locking element, a first locking recess in an interior surface of the cartridge body and a second locking recess in an exterior surface of the drawer opposite the first locking recess.